A hydrogen fuel cell is being used to provide power for a trigeneration facility, installed during a fit-out of an office building used by Transport for London. Kevin Stanley lifts the lid on the system

H

ydrogen fuel cells are commonly associated with the automotive and space industries. But they are also appropriate for providing energy for buildings. When Transport for

London (TfL) was looking to develop a location for head office staff at Palestra in central London, it decided to install a combined cooling, heating and power (CCHP) facility as part of the fit-out of the building. Detailed feasibility and viability studies suggested

that a hydrogen fuel cell would be the logical choice to provide sustainable energy for Palestra. The aim was to deliver the UK’s largest building-integrated fuel cell CHP as part of a 1MW trigeneration scheme. The fuel acts like a giant battery, with the hydrogen

extracted from the natural gas supply and oxygen from the air supplied to the fuel cell stack, made of plates separated by an electrolyte medium. The resultant electrochemical process has an output of DC electricity, which is fed into the building via an inverter providing a stable supply for the building’s IT equipment. The hydrogen for the fuel cell is created in a chemical process from the mains natural gas supply by a reformer built into the unit. There are losses associated with this process, but it is hoped that these will be offset by the efficiency of a device with virtually no moving parts compared with a conventional reciprocating engine CHP (RECHP). Says Andy Stanton, head of sustainable buildings

at TfL: ‘The unit we visited in Germany was actually fed by gas from a large anaerobic digester composting local food waste.’ The fuel cell has two heat output streams, one that

feeds a thermal storage vessel supplying the building’s heating and an absorption chiller, and a second that pre-heats the building hot water. Another by-product is pure water, most of which is reused in the hydrogen